j'l ||"i» ^^mmmmmmmn'm 





Class 

Book 



copnoGwr DEPosrr 



NOTES 



ON 



MECHANICAL DRAWING 



PREPARED FOR THE USE OF 
STUDENTS IN 



MECHANICAL, ELECTRICAL AND 
CHEMICAL ENGINEERING 

AT THE 

UNIVERSITY OF PENNSYLVANIA 



V, BY 
HORACE P.IfRY, B. S. in E. E. 

ASST. PROF. OF IV^ECHANICAL DRAWING 



PHILADELPHIA 

1912 




4'^ 



^-,^ 



COFTTUGHT, 1912, 

BY 
HORACE P. FRY. 



FOURTH EDinOX. 



gClA32090 



PREFACE. 

Mechanical drawings are required in all constructive work. 
In making such drawings, strict adherence to the principles of 
projection, accuracy and neatness in execution remove all doubts 
as to what is intended and makes a drawing perfectly clear to 
all accustomed to reading them. 

The matter contained in these notes is not an exhaustive 
treatise on mechanical drawing, but is intended to supplement 
the class instruction and should be referred to constantly by the 
student in his work. 

These notes contain recognized standards and conventions 
used in American practice, together with tables and other infor- 
mation valuable on the drawing table. The student will be held 
responsible for his work being done as directed in these notes. 

Questions are continually arising in the student's mind as to 
just how to represent certain conditions, and it is his duty to answer 
these questions for himself by referring to these notes before ques- 
tioning the instructor, as the latter 's time should be given to per- 
sonal supervision of the work each student has in hand. 

All drawings, when completed and handed in, will be exam- 
ined for execution, projection, arrangement and numerical errors, 
and any corrections required will be marked in pencil by the checker. 
Attention is called to the errors by means of the paragraph numbers 
under the subjects. The student must make corrections, or a new 
drawing, before the work will be finally accepted. Redrawn or 
corrected drawings must be returned not later than the return date 
stamped on the margin. 

Drawings, tracings and all other papers handed in by the 
student must bear his locker number with his name under it in the 
extreme upper right-hand corner, using neatly printed letters and 
figures yq" high. On drawings and tracings these should be placed 
on the long margin. See forms under Size of Sheets. 



(3) 



THE COURSES IN DRAWING 



The work in drawing extends over four years and is divided 
as follows: 

FRESHMAN COURSE— 492. Copying simple drawings 
accurately to familiarize the student with the handling and uses of 
the instruments. The principles of Orthographic Projection. 
Making simple mechanical working drawings from blue prints of 
free-hand sketches. Sectioning and shading. Free-hand lettering. 

SOPHOMORE COURSE— 493. First Term. Making more 
intricate working drawings from free-hand sketches. Tinting. 
Tracing. 

Second Term. Making working sketches on cross-section 
paper from parts of machinery in the laboratory-, the dimension of 
the parts to be found by measurement, the only tools being pencil, 
two-foot rule and calipers. 

JUNIOR COURSE— 494. First Term. Making detail and 
assembly working drawings from sketches made by the student 
in the previous course (493). Tracing and blue-printing the 
same. 

Second Term. Constructing combinations of mechanism, with 
restrictions, from data furnished and making drawings of the same, 
exact calculations for strength being a secondary consideration, the 
parts being proportioned empirically, the primary considerations 
entering into the construction being those governed by the kine- 
matic side of the proposition and the student's inventive ability. 

SENIOR COURSE— 517. Original sketches and calculations 
of the parts of some hoisting machine of an approved type, such as 
a crane, hoist, etc., are made by the student from which he must 
lay out an assembly drawing and detail working drawings and 
make tracings of them. In this course a student does individual 
work and is left largely to his own resources, his previous training 
being the main guide. The entire year is devoted to this subject. 



(4) 



INSTRUMENT LIST. 



Each student will provide himself with the following articles 
before he will be allowed to begin his work : 

A. Drawing instruments contained in set No. 2050 made by 
Theo. Alteneder & Sons, Philadelphia, as follows : 

No. 1404, 5|" compass, pen, pencil and lengthening 

bar, fixed needle point leg. 
No. 1530, 3 J'' bow spacer. 
No. 1532, 3 J" bow pencil with needle point. 
No. 1533, 3i'' bow pen with needle point. 
No. 1614, 5'' ruling pen. 
Nickel-plated lead case. 

The above to be contained in a morocco covered case having 
two metal hinges and clasps. (See Fig. 1.) 




Fig. 1. 

B. Triangular Box-wood scale having the following scales thereon: 

12'', 9\ 6\ V, 3', 2\ \Y to the foot, and 50 parts to the 
inch divided the full length of the scale. 

C. One 8"— 45° celluloid triangle. Not less than ~h" thick. 
One 12''— 60° celluloid triangle. Not less than ,Y thick. 

(5) 



D. 



F. 
G. 



H. 
I. 



K. 



L. 

M. 
X. 




One celluloid irregular cur\'e. as shown in Fig. 2. (K. and E. 

No. 19.) 
T square, 30' blade (not set in head). Blade 

have a celluloid edge. 
Two 6H Kooh-i-noor or Castell dra\s*ing pencils. 
One Faber's improved ink eraser ^small). 
One Faber's ruby pencil rubber (large). 
One Art Gum cleaning rubber (large). 
One dozen f " thumb tacks (thin head, K. &: E. Ideal). 
Drawing paper. (This can be purchased in the Fig. 2. 

Department Supply Room 212.) 
Reinhardt's Free-Hand Lettering, for Draftsmen, Engineers 

and Students. 
Drawing board, exactly 23" x 31" with cleats on the back, face 

of board must not be shellacked. Each cleat to have a 

3' X 1^" slot cut through next to board. Slots must be 

in line and about central of the cleats. 
One bottle of black waterproof drawing ink. Higgins' or 

Steuber's. 
One erasing shield. Must not be polished on both sides. 
One drawing package (wallet, lettering paper, file, penholder, 

pens, inkrag). procurable in the Department Supply Room. 



Note : — The above materials must be brought to the first 
session of the class in Course 492. 

Ever}- article itemized in the foregoing list has a specific pur- 
pose and must be used accordingly. 'See Fig. 3 for use of triangles.) 

A*_^ TO OBTAIN ANGLe^,^-— *A 
^ - *0- OF \ 5* AND 75" -5° «^,^\ 

-V.XwiTH TRIANGLES^ , ^ / ^^^ 




Fig. 3. 



Chisel points must be used on ail instrument leads and pencils. 

Cut the wood back for IJ" exposing the lead for f ", then flatten 
it by rubbing opposite sides on a file, then bring to a knife edge by 
using a slight rocking motion. 



SIZE OF SHEETS. 1. All 

drawings required in Courses 492 
and 493 are to be made on sheets 
10" X 14:", trimmed exactly to size. 
Complete the drawing before trim- 
ming it. For Forms see Course 492 
and Course 493 below. 

2. A number circle is to be 
placed in the lower left-hand cor- 
ner of each drawing in Courses 492 
and 493. The number of the 
sketch, from which the drawing 
was made, is to be placed in the 
upper half of the circle and the 
class section in the lower half as 
shown in Fig. 4. 

3. Course 492. — First Term: Use the form shown in Fig. 5. 
For lettering on lower margin see Fig. 25. 




Fig. 4 







''i*^ /^YA/esme \ 






\/L 






® 


\ 

SEE LETTER/NG AND TITLES EOR 
THE rORM OF LETTERS FOR YOUR 
/N/T/ALS OA/ THE MARGIN. 
THEY ARE eo" LETTERS, HEAVY 
L/NES, MADE l^/TH A RUL/NG REN; 
NOT RREEHAND. 

THE LAST LETTER 7X> BE TANGENT 
TO A GO^L/NE EROM CORNER OR 
BORDER. OM/T L/NE. 


/ 






H«^ A.S/<f 1 



Fig. 5. 



34^ 



"* PLACE TITLE HERE 

SEE LETTERING ANDTITLES 



Fig. 6. 

Course 492, Second Term ] tt ^i. r i. - ^- ^ 

r^ Af^-y T^' ^ rry \ Use thc lomi shown m Fig. 6. 

Course 493, First Term J ^ 

Course 493, Second Term. Sketching (see Figs. 26 and 27). 

Course 494, First Term. Use Department standard sizes. 

Course 494, Second Term. Use Department standard size A. 

See plate G for special form of title. 

Course 517. Use Department standard size A, unless other- 
wise directed. See plate H for special form 
of title. 

DEPARTMENT STANDARD SIZES. All drawings and 
tracings called for in any Department work, when trimmed, must 
be of one of the sizes shown in Fig. 7, unless specific orders to the 
contrary are given. Each tracing must have on the long margin, 
in the low^er right and inverted in the upper left-hand comer, the 
letter indicating the size of sheet and the number of the drawing 
as assigned from the index. Block letters and figures f " high are 
to be used for this notation. (See Fig. 24.) Index numbers will be 
assigned by the instructor when tracings are completed. 




234 



SHEET 


SIZE 


W 


L 


A 


20" 


28' 


B 


14' 


20" 


E 


10" 


14" 




PLACE TITLE HERE 

3EE LETTERINSAMoTlTLES 



E-1234 



Fig. 7. 

TRIMMING. Trim the drawings with a sharp penknife, 
using the lower edge of your T square as a guide and the back 
of your drawing board to cut on. Never use the face of board 
or table top. Trim tracing cloth with shears, leaving Y outside 
of margin all around; trim to size after the tracings have been 
examined and corrections made. The corrections in pencil must 
not be erased. 

Drawing sheets that are off size or carelessly trimmed or with 
thumb tack holes in the margin will be rejected. 

THE ESSENTIALS. In making a mechanical drawing the 
essentials are accuracy, clearness and neatness, as the object of 
such a drawing is to enable one to make the part or combination 
picture, without any other information than that contained on the 
drawing. The workman constructs as the drawing shows, not as 
the draftsman may have intended to show. 

ARRANGEMENT OF VIEWS. 1. All drawings are to be made 
as though the object were situated in the third angle and the views 

are to be arranged accordingly. (Faunce's Descriptive Geometry, Fig. 1.) 

Assume the object, of which a drawing is to be made, to be 
surrounded by a glass box (see Fig. 8). In other words, the planes 
of projection arc between the eye and the object in third angle pro- 
jection. Suppose the object to be projected orthographically on 



10 




FIG. 6 
each face of the box. Imagine one of the faces A B C D to coincide 
\\-ith the plane of the paper and revolve each of the others, about its 
intersection with that plane, until they are all in the plane of the 
paper, then the views will be in their proper relative position. The 
names and positions of the views thus projected are shown in Fig. 9. 



PLAN OR 
«— I TOP VIEW 







A 












6 












LEFT SIDE ^lEW FRONT VIEW 


RI€HT SIDE VIEW^ 


BACK VIEW 






1 ^ 

1 ) 

1 y 


' 




X 








(•1 


1 

1 




i 

1 


1 








OR ELE\ 


/A 


T 


IONS 














D 






BOT 


TC 


)M 


C 













VIEW 



FIG 9 



THE VIEWS MARKED THUS X 
ARE THE ONES MOST USED 
IN PRACTICE. THE OTHER 
VIEWS AND THOSE ON 
OBLIQUE PV_AN1E5 ARE USED 
WHEN CONDITIONS REQUIRE 
THEM 



11 



CHOOSING THE PROPER SCALE. 1. Before beginning 
the drawing, decide what views are necessary to clearly show the 
object. The object should be drawn either full size (never larger) 
or 9\ 6'\ 4^ 3", 1\ \\\ or V to the foot, the standard scales used 
in machine drawing. 

2. Lay out the sheet so that the views, when properly placed, 
will leave room for the title. Move the views from the center of 
the paper rather than reduce the scale. The following method for 
determining the scale will generally be found convenient : 




NOTE 

/ILL DRAW/f^SS 
MUST BE MADE 
W/TH THE BASE 
LINE r/IC/NG 
THEBOTTOM 

OR RIGHT 
H/^ND MAR&/N. 
LAYOEFy^LL 
CENTER LINES 
ANO CONST/fLfO 
FROM THEM. 



Fig. 10. 

Suppose the rectangles in Fig. 10 to represent the least areas 
which will contain the different views desired. The dimensions 
of the rectangles being the overall dimensions of the object to be 
drawn. If A+B <Li, the drawing can be made full size provided 
C + D<Wi. If not, multiply the dimensions (Li and Wi) of the 
paper by the quotient of 12 divided by one of the scales, 9, 6, 4, 3, 
2 or 1^, on the Boxwood Scale, until the new Li>A+B and the 
new Wi >CH-D. The scale that will give this is the scale to which 
the object can be drawn, or the reciprocal of the quotient is the 
size that the object can be drawn. 

3. Never combine the words size and scale. Either half 
size or scale ()" = V \ not scale half size. 



12 

4. The distance Li — (A+B) is to be divided between the 
spaces H, J and K as desired, and the distance Wi — (C +D) is to be 
divided between the spaces E, F and G. 

5. Make the distances (F and J) between the views not less than 
y or more than 1|", depending on the space required for dimensions. 

The rectangles referred to are not to be used in the actual 
laying out of the views. The center lines of each view are carefully 
located and from these the drawing is accurately constructed. 

LINES. 1. All drawings are to be made with a 6H sharp 
chisel pointed pencil and then inked with black India ink. The 
pencil work is to be clear and distinct and have a finished appear- 
ance before the inking is done. It is not necessarv* to pencil cross 
hatching or dimensions. The former may be done lightly freehand 
as a guide. 

2. Full lines are drawn for all visible edges. See Fig. 11 for 
width of line. 

3. Dotted lines are used to show hidden edges, and should 

v\sie>\_E: OR FLJL_L. i_\rsie. 

L-IGHT \_irvlE:, RATIO I T0 3 5H/\D^ L_\Ne. 



IMVlSlBl_E: OR DQTTEID Uirsi^S. 
Br.e:/^v^ ^Jol^sJ~^s wt-tezrvi l_irviEis> /\.f=iE: A d o -^^ c: ei isj t 



CEIMTEIR L_INie 



DIMEINSIOKI L_\rNiE: 



CONSTRUCTION 1_\N^E: 

iRRe<3UL_/\R line:. 

Fig. 11. 

be drawn when the clearness of the drawing is thereby furthered. 
(See Fig. 11.) These lines are in reality short dashes with spaces 
about i the length of the dash. The first and 
last dash of a dotted line should touch the Hues 
at which the hidden edge actuallv terminates. 
(See Fig. 12.) 

4. When parallel dotted Hues he close together, 
stagger the dashes and spaces as shown in Fig. 11. 
Fig. 12. The eve then can more readilv follow the Hnes. 



THU5_ 
NOT 



13 



5. The full lines in the two views, Fig. 13, represent lines in 
full view, and the dotted lines hidden ones. If the drawing is too 
much complicated by showing all the hidden edges, some may be 
omitted, provided the clearness of the drawing is not impaired. 




Fig. 13. 



6. Center lines are long dash and dot black lines somewhat 
lighter than the outline. (See Fig. 11.) They are drawn through 
all axes of symmetry, the centers of all holes, bolts and rivets and 
where dimensions are to be given from some fixed line. The break 
should not occur where a line is crossed. (See Fig. 13.) 

7. Different views of the same object are sometimes, though 
not necessarily, connected by center lines. (See Figs. 13 and 15.) 

8. Irregular lines are used to denote a break when a portion 
of a view is shown in section. (See Figs. 11 and 15.) 

9. Construction lines (see Fig. 11) are fine dash lines and 
are used largely in elementary work; they connect the projections 
on two adjacent planes. These lines should not touch the points 
between which they are drawn. 

10. Adjacent part lines are drawn like construction lines. 
They are used to show a part that is adjacent to the piece drawn. 



14 



SHADE LINES. 1. To distinguish readily between depressed 
and raised portions of an object, and to make the drawings stand 
out, some of the Hnes are made heavy. The light is supposed to 
fall on all views of the object, from the upper left-hand comer of 
the drawing, in parallel rays, at an angle of 45° with the plane of 




Fig. 14. 

the paper as shown by the arrow^s to the left in Fig. 14. The divi- 
sion between light and dark surfaces is indicated by a heavy Hne 
about three times as thick as the outline. No account is taken of 
the shadows cast by one portion of the object upon another. In 

many cases the position of shade lines is entirely conventional, for 
example, in Fig. 13 the lower lines of the right-hand view, do not, 
strictly speaking, represent the divisions between a light and a 



15 

dark surface, yet it is the custom to shade them as shown. A 
system of placing the shade Hues should be adopted and adhered 
to. Place all shade lines outside the outlines of the figure. 
A line common to two surfaces is not shaded when both 
surfaces are visible. Shade the views independently of each 
other. By placing a 45° triangle on the T square (see Fig. 14) 
and assuming the hypotenuse to be the ray of Hght it is easy to 
determine, by sliding the triangle along the T square, on just 
which surface the light does not impinge. See Fig. 11 for width 
of line. 

2. To shade a circle or arc always move the needle point of 
the instrument, without changing the radius, down to the right 
at an angle of 45° and a distance equal to the desired thickness of 
the shade line. Do this by eye. (See Fig. 14.) This will make 
the shade line blend into the outline at the proper place, i. e., where 
the light ray is tangent to the curve. By placing the needle point 
in the original center and springing the pen slightly outward, the 
space between the original and eccentric curve can be filled in easily. 

3. In cases where each end of a shaded arc joins a shade line 
the arc should be shaded by changing the radius and not moving 
the needle from the original center. 

4. Pencil lines are not shaded. 

INKING IN. 1. The majority of beginners make the mis- 
take of drawing very fine lines; they look neat but are not prac- 
tical. If the nibs of the pen are forced close together the ink will 
not flow readily and the result is a fine gray line. A fairly heavy 
black line is correct, see Fig. 11; this may be obtained by opening 
the nibs of the pen so that the ink flows readily. 

2. The outside of the pen must be kept free of ink. Never 
allow ink to harden in a pen; wipe frequently, and when through 
using see that the pen is quite clean. Do not scrape with a knife. 

3. When inking a drawing, first draw all circles and arcs, 
shading them a,s you go, after that draw the light straight lines, and 
finally the shaded straight lines. Dotted lines are not shaded. 
Lines, letters and figures must be black. If they have been 
lightened by erasure go over them until they are black. 

4. If the surface of the paper has been roughened by erasures, 
so that ink will spread, it can be restored by rubbing with a soap- 
stone pencil, ivory, bone, the finger nail, or a piece of hard surfaced 
paper. 

5. Keep your paper and materials free from dust and particles 
of eraser to avoid blots and errors. Dust the drawing frequently. 



16 




17 



DIMENSIONING. 1. In dimensioning a drawing, full light 
lines are drawn to connect the points between which a dimension 
is to be given. The lines are terminated by arrow heads, and the 
dimension is written in a break, usually but not necessarily in the 
center of the line, provided for that purpose, as in Figs. 11 and 15. 
Dimensions should be kept in line. (See Fig. 16.) 

2. Arrow heads are to be made with a fine writing pen. They 
should be small, neat and sharp, and touch the line to which they 
refer. (See Fig. 16.) 

3. Figures. — All dimension figures on a drawing should be 
as near the same size as possible and not in proportion to the size 
of the dimension or drawing. Figures ^" high are large enough 
for all practical purposes. The figures in the numerator and denom- 
inator of a fraction should, for clearness, be as large as the whole 
numbers. (See Fig. 16.) 



make: figure: s 
— 5' 



JVf 

4- 






Mr 



THUS laS^SGTSSO 

7 



(a^Fini^hed- 



FiG. 16. 



8 



COKVJ 
- inpk 






76 






:^P/pefap 




Fig. 17. 



4. Figures when printed with lettering, as in a note or title, 
are made as high as the capitals. 

5. Figures must not be placed on top of lines, keep them in 
the open. 

6. When the space, in 
which a dimension is to be 
placed, is very small, the 
arrow heads may be re- 
versed and placed with the 
dimension outside the space as shown in Fig. 17. When neces- 
sary from lack of room a dimension or note may be written in a con- 
venient place and connected to the required point by a straight 
leader. Such a leader should always have an arrow head to indi- 
cate the point to which the dimension or note refers. (See 
Fig. 13.) When a dimension is placed on a section the cross- 
hatching is omitted at that point. (See Fig. 15.) Dimension 
a drawing before cross-hatching it. 

7. Fractions must always have the dividing line made thus: 
f ", never Vs'^ and the figures must not touch the line. 



18 

8. Extension lines are full fine lines used to prolong the lines 
of a drawing in order to place a dimension away from the picture 
or at a more readable place on the picture. They should not quite 
touch the drawing that they may not be mistaken for part of it. 
Fig. 15 illustrates the use of extension lines. 

9. Dimensions may be given directly on the picture, but 
this frequently crowds the drawing too much. Dimensions should 
be placed outside the picture wherever clearness is gained thereby, 
using extension hnes between which the dimensions are given. 
Dimensions must be kept in hne as shown at the top of Fig. 13 and 
in Fig. 16. 

10. Dimensions must always be placed at right angles to the 
dimension line, and for convenience should read only from the 
bottom and right-hand side of a drawing. (See Fig. 15.) 

1 1 . Dimensions of machine parts are usually given in inches, 
thus: 2|", 27", the inch mark being placed after the figure. In 
large w^ork, such as roof trusses, dimensions over two feet are given 
in feet and inches, thus: 4'— 0", 20'— 8|", 3'— 0|". The dash 
is essential to avoid errors. 

12. All necessary dimensions must be placed on a drawing 
and care taken to avoid repetition. Give dimensions from finished 
surfaces wherever possible, from center lines, and from one center 
line to another, as in locating holes, etc. The size and location of 
holes must be given on the circular view. Center lines must never 
be used as dimension lines. Give dimensions to full lines, in 
preference to dotted ones, wherever practical. Over-all dimen- 
sions are useful in getting out material and should be given. 

13. Useful dimensions are those which are of most service to 
the user of the drawing who should never be required to do any 
calculating. A little thought as to the process the material must 
undergo in the construction of the object, will quickly determine 
what dimensions to give. 

14. Distribute the dimensions among all the views and do not 
crowd too many into one. Select the dimensions best suited to 
the views. 

15. In giving the radius of an arc of a circle, the arrow head 
is placed only in the arc never at the center. The dimension line 
should be drawn radially but need not extend to the center. When 
a complete circle is on the drawing, always give the diameter, as 
in Fig. 13. 

TABULATED DIMENSIONS. 1. Parts that are similar in 
shape but different in size should have their dimensions tabulated 
as shown in Plate J. A drawing of one of the parts being sufficient. 



19 



Abbreviations. The abbreviations and symbols most com- 
monly used in practice are shown in Fig. 18. 



C^/s/re/x' TO ceA/TS/^ ^fo^ 

C//?C(/IAR /=^/TCH Cf? 

Qf^cuMreffe/vce C/rcum. 

D/AMET/fAL /='/TCU D. /? 

0/amjET£/p _ P/am. 
/^/rr rt or ' 

fy/V/SH MARK h 



^^'XAOONAL Hex. 

/ncmss //?s. or '' 

/ns/ds / v5! 

Le^r HAND L. // 

OUTS/D^- O. S. 

P/rCH C/RClf- P/AM. PCP> 

f^A D/us /xhc/,or /P 

PiGHTHAA/D R. H. 

Squarje Sa. 

77y/?£AOS T/7CfS, 



Fig. 18. 

Finish marks (Fig. 19) must be placed on all 

finished surfaces. They are made with a writing 

^y pen and should read from the bottom of the 

^^ xf ^^ drawing only. (See Fig. 15.) Finish marks indi- 

/ cate that the surfaces marked must be machined, 

Fig. 19. ^*^^ necessarily polished, to the exact dimension 

given. The casting or forging is made full to 

allow for machining. When the whole piece is to be finished all 

over, omit these marks and print "finished" in the general title. 

(See Titles.) 

SECTIONS. 1. As the object of a drawing is to represent 
the exact construction of the machine or part drawn, it is often 
convenient for clearness to represent some of the views or parts of 
them as sections through the object. Thus, in Fig. 15, the upper 
half of the right-hand view represents a section on a plane A-B 
normal to the plane of projection of the circular view. That is, 
we assume the near portion of the upper half of the object (as 
shown in the right-hand view only) to be cut away, back to the 
section plane and represent the object as it would then appear 

2. Place a note directly under the view stating where the sec- 
tion is taken; thus, Section on A — B, Section on X — Y — Z. Use 
inclined lower case letters. 



20 

3. When the Hmit of a part in section is at a plane through 
the center Hne, the center Hne is made a full line as far as the 
section extends, and shaded if the conditions require it. 

4. When the limit of a section is not at the center line, an 
irregular line (Fig. 11) is drawn to show a fractured surface. 
(See Fig. 15.) The latter method is frequently necessary to more 
clearly show the detail of the interior; for example the key and 
key way in the illustration. 

CROSS-HATCHING. 1. All portions of the material cut 
by a section plane are cross-hatched by lines making an angle of 
45°, except where otherwise shown in the "Conventional Standard 
Cross-hatchings" Plate A. Cross-hatching is done after a drawing 
is fully dimensioned, omitting it where the dimension is placed. 
All sections of the same piece, in the same plane, are cross-hatched 
in the same direction. Cross-hatching never extends over a full 
line. 

2. When two or more pieces, of the same or different mate- 
rial, show in a section adjacent to each other, the cross-hatching 
must be drawn in opposite directions. (See Figs. 15 and 30.) 

3. Care should be taken to space the cross-hatching uniformly. 
This is readily done by eye, after a little practice on a separate 
sheet of paper. The appearance of a drawing, which is otherwise 
faultless, is often spoiled by poor cross-hatching. 

4. Section lines should be somewhat finer than the outline 
and not too close. Use about a y^'' space. 

Plate A shows the system of conventional cross-hatching to be 
used in this work. Note spacing and width of line. 

5. When a section is taken longitudinally through a Shaft, 
Axle, Bolt, Spokes of Wheels, Ribs or Webs, these are not sectioned 
but are drawn full as though the cutting plane did not pass through 
them. (See Fig. 15.) 

6. When the whole of a shaft, bar, channel or other long piece 
cannot be shown in its full length, it is represented broken as shown 
in Fig. 20, the break showing roughly the outline of the cross sec- 
tion of the piece. 



21 



CONVENTIONAL 
STANDARD CROSS-HATCHINGS 





CAST STEEL 




BRASS 




ALUMINUM 




LEATHER 




WOOD 



y///////////. 


'////////////. 


y//////////y 



RED BRICK 





CAST IRON WROUGHT IRON MALLEABLE IRON 




WROUGHT STEEL 






BRONZE 




BEARING METAL 




A5BEST05 



LIQUID 



V/M/////////A 



A 



FIRE BRICK 
Plate A. 




COPPER 




WIRES 




GLASS 



^S 



^ 






STONE 



?2 





.H/\FT 



BAR 





WOOD 



PIPE 



T 



/MNJGL-E IRON 



tee: IROM 



I 



CHANNEL. IRON 



I BEAM 



Fig. 20. 



TINTING. 1. When a large part of a drawing is in section 
it is often more convenient to tint the drawing than to cross-hatch 
it. If this is done the drawing should be fully inked in with water- 
proof ink, omitting dimensions until the tint is applied. 

2. The drawing should be freed from pencil marks and well 
cleaned before tinting, as the tint is readily removed with a pencil 
eraser. A cleaning rubber will tone it down if too dark. 

3. It is well to go over the portions to be tinted with a brush, 
using clear water, just before applying the tint ; this will prevent the 
tint from dr^dng too rapidly. Make the tint light, then, by going 
over it again, if necessary, the proper shade may be obtained. 
Stir the tint in the saucer with every dipping of the brush. Remem- 
ber that the process is that of tinting and not painting. 

4. A smooth tint will result if it is done quickly, keeping a 
drop of tint on the paper just ahead of the brush and leaving the 
part tinted practically dry. An excess of moisture remaining will 
cause the tint to drv" blotchy. If the tint runs over a line, brush 
back quickly with the finger. 



23 

5. In this tinting work use the moist water colors named for 
the materials in the list below. 

The color mentioned first, for a given material, should predom- 
inate in mixing the tint representing that material. In any case 
a very small quantity of color will suffice. 

Cast Iron Paynes Gray. 

Wrought Iron Prussian Blue. 

Wrought Steel Prussian Blue and Crimson Lake. 

Cast Steel Crimson Lake and Prussian Blue. 

Brass Gamboge. 

Bronze Gamboge and Crimson Lake. 

Copper Crimson Lake and Gamboge. 

Babbitt . Thin Ground India Ink. 

Leather Thin Ground India Ink and Burnt Sienna. 

Wood Burnt Sienna. 

Glass Prussian Blue and Gamboge. 

6. Lines and dimensions may be placed directly on the tinted 
surface if necessary. 

7. When the area to be tinted is large, the paper should be 
stretched before starting the drawing. This is done by thoroughly 
wetting the paper and pasting it, along the edges, to the drawing 
board. 

LINE SHADING. 1. Line shading is used to represent more 
clearly or more quickly the nature of the surfaces of which the piece 
is composed. 

2. This method is often used where the number of views is 
limited or where it is desired to represent to those who are not 
familiar with the principles of mechanical drawing, the construc- 
tion of a machine. 

3. Book and magazine illustrations and Patent Office draw- 
ings are also examples. 

4. The distribution of light and shade found in current practice 
in the case of a circular cylinder, can be produced by assuming the 
illumination to come from the opposite sources S and Si (Fig. 21) 
in parallel rays making 45° with the horizontal plane of projection 
and having their horizontal projections at 45° wnth the ground 
Hne. 



24 



LINE SHADING 




^ 



Fig. 21. 



25 

5. The brightest part of an illuminated object is that which 
reflects the rays of light directly into the eye of the observer. As- 
suming the light to fall as above described, and knowing the angle 
of reflection R must equal the angle of incidence I, reference to 
Fig. 21 will show that the high light must be 22 J ° around from 
the center line C L. At this point, and at this point only, a ray 
of light would be reflected normal to the plane of projection and to 
the eye of the observer. 

6. By the same reasoning it will be seen that the dark element, 
or no light, is 45° around on the opposite side of the center line 
C L, for at this point the light rays are tangent and there is no 
reflected light. 

7. Beyond this element the surface is slightly illuminated by 
the rays Si coming from below upwards as assumed. 

8. The limiting elements A B and D E (Fig. 21) are of the 
same shade. The shades received by all surfaces of revolution are 
shown by lines which represent the generatrix in various posi- 
tions, the intensity of the shade being effected by the thickness of 
the lines. 

9. First, ink the outline of the drawing with a uniform line; 
omit dimensions, dotted lines, shade lines and center lines, although 
the latter are always pencilled for construction. Second, ink 
the shading, the straight lines first, and then the curved ones. 
Avoid making lines fine or too close together. 

10. Practice line shading, suitable for the different surfaces on 
your drawing, on a separate sheet of paper and submit to your 
instructor for approval before you line shade your drawing. 

11. Examples of line shading will be found on Plates B, C, 
and D, which cover most shapes met with; study them and apply 
to your special case. 

12. Each drawing must have a general title as shown on blue- 
print sketch from which the drawing is made. 

13. If there are two or more pieces shown, place their respec- 
tive names under them. 

1 4. Do not use a knife on line shading ; use a rubber to erase 
errors, then restore the surface of the paper by rubbing it with 
another piece of paper. 



t 



26 




Plate B. 



27 







^p- R a/7c/ X to he founc/ Ay tr/a/ 

Scre\A/ threaaf^ t/?af c?re § or oyer //? c//a/?7efeK \^/?e/7 
c/rc7wn to 5ca/e, 5/?o(//c/he (^rakv/7 to t/pe exact 3/7t7/?e 
arpc/p/tc/?^ t/?e ci/r\/e of t/?e /?e//x /?e//?f /yey/ectea^, 
^/7^ 3/7aafe as show/^ c?t A a/7c/B . i/V/pe/? i/raer ^ D/c7/?7. 
use T/?e co^?ye/7f/o^7a//?7et/7oa^5 Ea/pc//^ 



Plate C. 



28 




Drai/y A-Canc/A-B 

- C-DlltoA-B 

Prolong ^trai^ht 

l/nes to meet A- B 

With radii X-A-C 

c?/7d^ o/?C~Dc/raw 

the arc5. 




DrawA-Car?^A-B DrawC-D //toA-B. DrawC-E 
J_ toE'H. Draw E~B. Pro/ony sTra/yhf //nes to 
E-B. W/fh rac^i/ X=CE a/^d 9^or/ C-D cthaw the arc6. 



Plate D. 



29 




F/anof/^oA 



Fig. 22. 



\ 



INTERSECTIONS. 1. The intersections of curved surfaces 
should be drawn as an aid to the understanding of a drawing. 

2. Descriptive Geometry treats of the methods employed in 
finding intersections, but the student unfamiliar with this subject 
can plot most of the simpler ones met with in practice if he observes 
the following instructions. 



30 

3. Fig. 11 shows two intersecting cylinders A and B with axes 
at right angles and in the same plane. I is their line of intersection, 
its shape being determined by plotting points. These points are the 
intersections of elements in the cylindrical surface A with elements 
in the cylindrical surface B. Element 1 of A intersects element 
1 of B at r and element 3 of A intersects it at 3"". Element 2 of A. 
see end \4ew, intersects element 2 of B at 2^, this point projected 
on the vertical plane is T\ and is the lowest point of the curve of 
intersection I. Intermediate points such as 5^' are found by passing 
planes in such a way that they cut elements from each cylinder, the 
intersection of the elements in any one plane being a point on the 
curve. For example, the plane X — Y at any distance S from the 
center line, see end view, cuts element 4^5^ from A and 6^5^, see 
top view, from B. The points 5^ and 5^ projected on the vertical 
plane determine 5"'. This point being the intersection of two 
elements, is a point on the cur\'e of intersection. Another point 7"' 
is determined by projection from 7^. 

4. A sufficient number of points should be plotted to determine 
the shape of the curve. Approximate the curve by drawing a light 
freehand line through the points plotted, as a guide for applying 
the Irregular (French) Curve. With the aid of the Irregular 
Curve a smooth cur\4ng line is drawn through the points. 

5. Cylinder B is hollow and has been broken away to show a 
hole cut through its lower portion. This case is similar to the pre- 
vious one, the difference being that the thickness of the cylinder is 
shown and the hole therefore intersects the inside as well as the 
outside surface of the cylinder B. 

6. The plane M — X, see end view, contains elements of the 
cylindrical surfaces that pass through the points 8^ and 9^ as well 
as the element of 8^^^ of the semi-cylindrical surface of the hole. 
These are the points in which the elements meet and if projected 
on the vertical plane, determine 8^' and 9^' which are points on 
the lines of intersections J and J^ 

7. Fig. 23 shows a pipe elbow with its center at O, intersected 
by an offset cylindrical outlet. In this case points in the Hne of 
intersection I are found by passing planes containing elements of 
the cylindrical surface and arcs on the surface of the elbow. Ele- 
ment 2 appears to intersect the elbow at b^, end view, but a plane 
passed through 2 cuts from the elbow, front view, the arc b^'2^'c^'. 



31 




Fig. 23. 



This arc is found by projecting the point b^ to the center Hne at b"' 
thus determining a point in the plane through which to draw an arc 
with O as its center. The element 2 lies in the plane of this arc and 
intersects it at V which is a point on the line of intersection Wy . 
The point V projected to the end view determines 2^, a point on the 
intersection that appears in that view. Pass any other plane as 
X — Y at any distance S from the center line. The points of the 
lines of intersection that lie in this plane are 4^' and 5^ in the front 
view and 4"^ and 5^ in the end view. A sufficient number of points 
are to be found through which curves of intersection may be drawn. 
8. Note that between 6"^ and V , front view, the Hne of intersec- 
tion replaces the portion of the arc of the elbow in this view. 



32 




33 



LETTERING. 1. Special attention should 
be given to lettering, as, when well executed, 
it adds greatly to the working value of a draw- 
ing. With care and constant practice any 
student can do satisfactory lettering. 

2. The lettering on all drawings, unless 
otherwise directed, is to be done according to 
the system described in Reinhardt's ''Free- 
hand Lettering," using inclined and upright 
letters of the ''Gothic" type in the heights 
shown on Plate E. 

3. The last half hour of each period in 
Course 492, first term, will be devoted to the 
practice of free-hand lettering. 

4. For the small lettering in descriptive 
matter, notes, dimensions and arrow heads a 
"Gillott No. 390" pen should be used. 

5. For the main title, large letters and 
when filling in a "Hewitt's Patent Ball 
Pointed Pen," No. 516F, is most suitable. 

6. Notes and descriptive matter should 
read from the Lower or Right-hand edge of 
a drawing and not in a diagonal direction. 

7. Index numbers on tracings are to be 
made as shown in Fig. 24. 

8. Initials on the margin of drawings in 
Course 492, first term, are to be made with 
a ruling pen and exactly as shown in Fig. 25. 



H'> M'm //////// ^ S: 



I 



'/ / W/K'/z/N j^f wrm 










\ 




1" 




M 


— 


\ 


1 




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t 




r 




1 




n r 




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Tr mTT 


Ml 






"Li 


— 




— 


— 




K 


— 







■ 


— 








I ' 1 


— 


i 




1^ 


1 




c 




1^ 








lilD 














1 






BLOCK LETTERS AND NUMERALS 

I'hioh, as shown, to be used for 
the index number on tracings. 


i 










— 


— 


1 






1 1 




















1^ -,i 


kV 





Fig. 25. 



Fui 



34 



TITLES. 1. Every drawing should have a general title (See 

Plate F) containing the following essentials : 

NAME OF THE PIECE. 
NAME OF THE MACHINE OF WHICH IT IS A PART. 

QUANTITY REQUIRED, MATERIAL. FINISH. 
SCALE, NAME OF DRAFTSMAN, DATE COMPLETED. 

2. Strictly speaking, any one piece of a machine is a detail 

of that machine, but should not be designated as such in the title. 

Name it in the title when no other parts are drawn. When several 

pieces of a machine are drawn separately on a sheet, it then becomes 

a detail drawing and should have a general title as follows : 

DETAILS OF 

NAME OF THE MACHINE OF WHICH THEY ARE PARTS. 

SCALES. NAME OF DRAFTSMAN. DATE COMPLETED. 

3. Sub-captions (see Plate G) must be placed under each 

piece on a detail sheet, they should contain the following essentials : 

NAME OF PIECE. 

QUANTITY REQUIRED, MATERIAL, FINISH. 

SCALE. 

4. If the scale is the same for all the details it should be omitted 
from the sub-caption. Avoid using more than three scales on the 
one detail sheet. 

5. Part numbers are frequently used as a substitute for names 
of pieces on a detail sheet. These numbers are necessary when 
the pieces are difficult to name concisely or are. numerous and 

similar. "Part number " replaces "name of piece" in the 

sub-captions. On the assembly drawing the numbers must appear 
in circles with leaders to the parts designated. 

6. A bill of materials should be placed on drawings that 

show several pieces assembled. Its form should be as shown on 

Plate G and should contain the following essentials. 

BILL OF MATERIALS. 

PRINCIPAL PIECE, QUANTITY REQUIRED, MATERIAL, FINISH. 

SECONDARY PIECE, QUANTITY REQUIRED, MATERIAL, FINISH. 

SMALLEST PIECE, QUANTITY REQUIRED, MATERIAL, FINISH. 

The " Quantity required " in the title would be the number 

of units wanted. A unit being an assemblage of all the pieces 
specified in the bill of material. 

The words " as shown " should be substituted for " material " 
and " finish " in the title when a bill is given. 

7. The Location of the Title on Drawings in Courses 492 and 
493 is shown in Fig. 6; Course 494, first term, in Fig 7, second 
term, on Plate K; Course 517 on Plate H. 

Note the varying heights of each line of words according to 
their importance and the symmetrical appearance of the titles. 



35 

roRMs F="OR -r»-rv-E:s 



PISTON ROD31 

aSTETEU FINISHED 



H^ 



HAur size: >\.s. knona/. a-is-iaos , 



OUTBOARD BEARINe^II 
Vxg''metropolitan engine'h*: 

I C>KST IRON. FINISH A3 I N D I C ATE D_|_. 

aCAUE 3=r M.Y. NAME |-4--»SOSZ^. 

— — — Vii 

ECCENTRICand sTRAP!M 

GX^y^SLlDE VALVE BLOWER ENGINE "E^i 

I OF EACH AS SHOWNZI^^v,3.'' 
ECCENTRIC CAST IRON FINISHED ZZ^^^^ 

STRAP PHOSPHOR BRONZE FINISHED AS SHOWN 

// , ; 

5CAUE 6=- I W.H.O.D\DIT. 6-30-l905..>^ 

^ ^(^ 

DEIT'AIL.S OF ^f^ 

\0 "TOM UIB CRANEI^ 



sc/m^e: a'^'^i' name S'-i7-i903_^ 
DETA\LS OF ^^ 

a^'GOVERNORM^ 

i 



FOR A\R COMPRESSOR!^ ^^,cg 
FULL size: I.DREWIT IO-3\-\S05.~Z 



Platk I' 



36 



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ASSEMBLY DRAWINGS. 1. When a portion or the whole 
of a machine is drawn showing the various parts joined together 
in their relative positions, it is known as an assembly drawing. 



40 

2. The designer, in laying out a machine, must make the 
assembly drawing first, the details being drawn out to larger scales 
afterwards. On assembly drawings it is often well to show sec- 
tions on different parallel planes in the same view. 

ERECTING DRAWINGS. 1. Assembly drawings which show 
all the parts of the machine in place, but neglect the unnecessary 
and minute details of construction, are known as erecting draw- 
ings. These are frequently drawn to a scale smaller than that of 
the original design. They are sent with a machine to be used in 
setting it up at its destination. 

2. Drawings of this class should be so dimensioned as to 
enable the erectors to distinguish and place the various parts in 
their proper relation to each other. 

TRACING. 1. For reproducing drawings, without injury to 
the original, tracings are made upon tracing paper or cloth. 

2. Tracing cloth or linen is used almost exclusively, owing to 
its wearing qualities. It is a specially prepared linen fabric, having 
one side glazed and the other rough, the former being known as 
the smooth side, the latter the dull side. Tracings can be made 
on either side of the cloth but the side used should be thoroughly 
rubbed with powdered chalk or soapstone to remove greasiness 
and permit the ink to.* 'take" more readily, the excess chalk being 
thoroughly cleaned off before starting to trace. Tracings partly 
inked may be rubbed with powder, if the ink fails to take, without 
injury to the lines. 

3. The dull side of the cloth is to be used for all tracings unless 
otherwise directed. It is easier to draw pencil lines on the dull 
side when making additions to views or checker's corrections. 
Drawings made on the dull side will make the tracing lie flat after 
removing from the board and not roll up, an objectionable feature 
caused by drawing on the smooth side. 

4. Fine thin lines are to be avoided when making a tracing, 
as the light, in printing, will burn through such lines, causing the 
blue-print to appear blurred and indistinct. Read "Inking In" 
paragraph 3. 

5. Erasures may be made as on paper, the pencil eraser usually 
being sufficient. The ink eraser should be used with care to avoid 
cutting the fabric. Place a triangle or other hard surfaced article 
under the cloth when erasing. Wherever an erasure has been made, 



41 

the place should be rubbed with a soapstone pencil or powdered 
chalk before re-inking to prevent the ink from passing through 
the cloth. 

6. Ink dropped upon tracing cloth should never be blotted, 
but should be smeared as quickly as possible with the thumb, 
using a scooping up motion. When the smear has dried it is read- 
ily erased with the pencil eraser. 

7. Pencil marks can be removed with the Art Gum cleaning 
rubber without afifecting the ink lines. Before trimming tracings 
read the paragraph on Trimming. 

BLUE-PRINTS. 1. Original drawings are seldom sent into 
the shop. Duplicates in the shape of either blue-prints (white 
lines on a blue ground) or white prints (blue or black lines on a 
white ground) are used in place of them. 

2. These prints are moderate in cost and can be produced in 
endless numbers. They are obtained by exposing a sensitized paper 
or cloth to light rays. A positive tracing of the original drawing 
on a translucent medium such as tracing cloth or paper, is inter- 
posed between the light and the sensitized paper and in direct 
contact with the latter, the time of exposure depending upon 
the intensity of the light and the composition of the sensitizing 
emulsion. 

3, The age, or length of time since the paper has been sensi- 
tized modifies the time of exposure. The fresher the paper the less 
exposure required. The prints are fixed by immersing for about 
ten minutes in clear water. Special papers require the addition of 
chemicals to the fixing bath. Instructions for the treatment of 
such papers generally accompany them. 

SKETCHING. 1. The student will be required to provide 
himself with the following sketching outfit before he will be allowed 
to proceed with Course 493, second term. 

1 Department standard fibre sketch board and steel clip. 

1 Package Department standard cross-section paper -^^" ruling. 

1 — 3H lead pencil. 

1 Green pencil eraser. 

1-2 Ft. rule. 

1 Pair 6" firm joint inside calipers, good grade. 

2. The tools enumerated above are the only ones to be used 
by the student for making sketches. 



42 



3. The object of a sketch is to give, in as few views as possi- 
ble, sufficient information as to the shape and size of the machine 



3^S 



UNIVERSITY OF PENNSYLVANIA ^^^^^<^^^ 

MECHANICAL AND ELECTRICAL ENGINEERING. 



o 



o 



Mt'.i-.fir 



Kitoif.WMf.m 



iztn 




iuzci.l's^ut 



I 



Fig. 26. 



or the part represented to enable a draftsman to make complete 
working drawings. Sketches are to be made freehand on cross- 
section paper, ruled 10 divisions to the inch. 



43 



4. Each sketch sheet must contain the name of the machine at 
the top and directly under the views the name of the piece, quantity 
required, material and finish, and the part number in a circle. See 



O 



O 



3^5 



UNIVERSITY OF PENNSYLVANIA Na/7;ehere 

MECHANICAL AND ELECTRICAL ENGINEERING. 




Fig. 27. 



Fig. 26. The student's name, date completed and total time 
consumed in sketching all views of each piece are to be placed as 
shown on Figs. 26 and 27. 



44 

5. The size of the sketch should not be in proportion to the 
size of the object, but should be large enough to contain all dimen- 
sions without being crowded. When the piece is large or compli- 
cated, the various views should be placed on separate sheets. 

6. If more than one sheet is required, to properly portray the 
piece, page the sheets in the lower left corner as shown in Fig. 26. 

7. The piece should first be sketched by eye, endeavoring to 
maintain its relative proportions before taking any measurements. 

8. The dimension lines with arrow heads are then placed 
where the dimension figures will show to the best advantage. 
Finally the piece is measured and the dimensions placed in the 
spaces previously provided. 

9. In general, the same views, sections, etc., which would be 
used in making working drawings are used in sketching, except that 
in the latter many abbreviations are used. For example, in Fig. 
27 only one view of each detail is shown, the plan being omitted, 
and the abbreviations Diam. and Hex. indicate that those por- 
tions are round and hexagonal. In the same way Sq. for square, 
Oct. for octagonal, and other abbreviations are used. (See Abbre- 
viations, Fig. 18.) 

10. When a piece is symmetrical about an axis, a view of 
one-half of the object is often suihcient. (See Fig. 26.) By taking 
advantage of these and similar points, both time and labor are 
saved. 

11. The pieces are to be sketched separately and measure- 
ments taken independently, except in the case of large pieces 
when one student may assist another where needed. 

12. Directions given for dimensioning drawings are appli- 
cable to sketches, although it is better to give too many dimensions, 
than too few, as the student will not have excess to the machine 
when he makes the working drawings from his sketches. 

13. Rough castings should be measured to the nearest six- 
teenth and allowance made for draft, when this affects the required 
measurement. On finished work, measure as closely as possible. 
Judgment should be exercised when making measurements, espe- 
cially of rough work, as an apparently odd dimension may be due 
to the irregularities of casting or forging. 

14. Dimensions should be referred to center lines and to fin- 
ished surfaces rather than to rough ones. 

15. The radii of all curves should be given. To ascertain 
these, take a piece of paper and with a pencil mark the outline of 
the curve upon it, and then with a pair of calipers, used as dividers, 



45 

obtain the correct radius. When this cannot be done, take a wire 
or thin strip of lead and bend it around the curve, and with the aid 
of this mark the outhne on paper and proceed as before. 

16. Holes should always be located by their centers. Where 
there are several holes of the same size, similarly located in a piece, 
it is not necessary to give the diameter of more than one of them. 

17. Tapering and tapped holes should always be noted. The 
number of threads will be understood to be standard unless other- 
wise noted. 

18. When measuring the depth of holes, give the distance to 
the point where they begin to taper. (See dimension H on Fig. 31.) 

19. The dimension of a cavity, from which the open calipers 
can not be extracted, may be obtained by scratching a cross on 
each leg of the caliper and measuring the distance between their 
cexiters; extract the calipers and adjust the crosses to the distance 
read, the measurement across the caliper points is the one desired. 

20. All sketches will be checked with red ink and returned for 
correction. The corrections must be made and the sketch returned 
on or before the date stamped on the back. 

GEARS. 1. On Plates L and M will be found the conven- 
tional lines and notations for spur and bevel gears. 

2. For the theory of gearing and method of drawing various 
types of gear wheels, the student, when the occasion arises, is 
referred to one of the many books on the subject. 

George B. Grant's "Treatise on Gears," and Brown & Sharpe's 
''Practical Treatise on Gearing" and ''Formulae in Gearing," are 
published by the manufacturers. 



46 



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48 



SCREW THREADS. 




1 . If a point moves on the surface of a 
circular cylinder, so that its motion 
around the axis and parallel to the axis 
is uniform, the path of the point is a 
helix or screw curve. 

2. The method of drawing the 
helix is shown in Fig. 28, the true 
shape of a V and a square thread being 
shown. When drawing screw threads, 
except for very large diameters, it is 
not necessary to lay down the curve 
of the helices of which they are com- 
prised. Straight lines properly drawn 
from point to point and root to root 
answer all practical purposes. (See 
Fig. 29.) The standard thread shr )p=^ 
are shown in Plates N and O. 

3. To draw a screw thread lay off 
the pitch of the points accurately on 
one side. Draw shape of threads on 
that side. Locate any one point on 
opposite side. Draw the point line 
across, then draw all point lines 
parallel to this one. Draw shape of 
threads on opposite side. Draw root 
lines across. 

4. A right-hand thread is one that 
will cause a threaded piece to advance 

3 into a tapped hole when the piece is 
c turned clockwise. (See Fig. 29.) 

5. A left-hand thread will cause 
the piece to advance when turned 

both cases the threaded piece must be 



<-ROOT DI^M.— 
DIAM OF SCREW 

Fig. 28. 

counter-clockwise. In 

between the manipulator and the tapped hole. 

6. If a threaded piece is held horizontally with the axis at 
right angles to the body, the threads seen will incline away from the 
body from left to right for a right-hand thread and from right to 
left for a left-hand thread. Threads are understood to be U. S. 
standard and right-hand unless otherwise specified. 

7. The pitch of a single thread is the distance between two 
adjacent points. Or, in other words, the pitch is the distance the 
point would advance parallel to the axis in one revolution, e. g., 
single thread J" pitch, 4 pitch, or 4 threads per inch. (Fig. 28.) 

8. On double, triple or other multiple threads the lead is 
the distance from one point to the next point of the same thread 



I 

1 



49 



RIGHT HAND INSIDE AND OUTSIDE SCREW THREADS 
sirvi3L_E: V. DOUBEE V. sirNiei_E 5q. double sq. 




5IMC3 



DOUBi—E-v: sirs»G\-e SQ. doljbu-e: SQ 



LEFT MAMD INSIDE AND OUTSIDE SCREW THREADS 

Fig. 29. 

measured parallel to the axis. The distance between two adjacent 

threads is sometimes called the divided pitch. The lead is the one 

generally specified for the 

machine shop (see Fig. 29) ; 

e. g., double thread J'^ lead 

or 2 pitch; triple thread f '^ 

lead or IJ pitch. Triple 

thread 3 pitch, means three 

threads each making three 

revolutions per inch. 

9. The diameter of a 
thread is the extreme out- 
side diameter of the 
threaded portion of a 
piece (See Fig. v3() for 
sections through threads.) 




Fig. 30. 



50 



O^DIAM OF TAP 

R = ROOT DIAM. 

D = DRILL DIAM. 

H=" DEPTH DRILLED. 

T= DEPTH TAPPED. 
D=R, APPROXIMATELY. 
HIDDEN THREADS ARE 
ALWAYS INDICATED A5 
SHOWN AT X . 



H TAPPED HOLES. 1. The diameter of a tapped hole is 
the outside diameter of the threaded piece that would fit that hole, 
not the apparent diameter of the hole. (See Fig. 31.) 

2. Drill size for tap is 

the diameter of the hole 
which is drilled to prepare 
it for the tap, and which 
leaves the proper amount 
of stock for threads. 
Drills have a conical point 
which is 118° or, for all 
practical purposes on a 
drawing, 120°. Fig. 31 
shows the shape of the 
bottom of a hole which 
has been drilled. The 
hole in this case has not 
been tapped to its full 
depth. 

3. When a section is 
taken through a tapped 
hole, the inclination of 
the screw thread at the 

back of the hole is reversed. A little thought with reference to 
Figs. 29, 30, 31 and 32 will make this clear. 

4. Hidden threads are always represented by parallel dotted 
lines. (See nuts, Fig. 15, hole, Fig. 31, and bolt in Fig. 32.) 

CONVENTIONAL THREADS. 1. This method of showing 
screw threads is to be used, for clearness and economy, when the 
diameter of a thread, as drawn to scale, is less than |". (See Fig. 32.) 

CONVENTIONAL THREADS. ' ^ 




Fig. 31, 




Fig. 32. 



51 

2. Conventional threads, as shown in Fig. 32, are used for 
threads of all standards. It is not necessary that the number of 
divisions should correspond with the actual number of threads. 
If the thread is other than the U. S. Standard, or if the number of 
threads does not correspond with the standard number for that 
diameter, there should be a note to that effect, thus "13thds per 
inch," "Square Threads 4 per inch," ''Double Square Thread 2 
pitch," ''Triple V Thread V Lead," "f" Pipe Thread," "Taper 
Thread 14 per inch, taper x in. per ft." 

3. The spacing of the lines should be done by eye; pencil lines 
may be drawn to limit the length of the heavy root lines. The 
inclination of the lines should be practically the same as though the 
thread were drawn out to its actual shape. That is, for a single 
thread a point on one side should be diametrically opposite the 
adjoining root. For a double thread the point on one side should 
be diametrically opposite the point of the next thread. For triple 
threads the point on one side is diametrically opposite the next root 
but one. Fig. 29 will make this clear. 

4. Conventional threads are not to be used whenever a section 
is taken through two pieces which are screwed together (see A, Fig. 
30), both of which show in section, or when a thread is isolated 
(see B, Fig. 30), but cut by the section plane. 

5. Tapped holes are shown as in Fig. 32 by two circles, the 
inner one full and the outer one half full and half dotted. All 
threaded holes should have a note designating the size they are to 
be tapped, f '' Tap means that the hole is to be tapped to take a 
screw f " in diameter. 

SCREW THREAD PROPORTIONS AND TABLES. The 

standard forms and proportions of screw threads in practical use 
in the United States will be found on Plates N and O. 

BOLTS. 1. The standard proportions for bolt heads and 
nuts shown on Plate M were adopted by the Franklin Institute, 
December, 1864. 

2. Manufacturers have deviated slightly from these propor- 
tions, owing to the materials used in their manufacture not being 
commercial sizes. 

3. When drawing bolts and nuts, take dimensions from table 
on Plate Q and use the method shown on Plate P for approxi- 
mating the curves which are, in reahty, portions of hyperbolas, 
the results of chamfering. 

MACHINE SCREWS. 1. Standard machine screws are shown 
on Plate R. The values in the table are very close to the A. S. M. E. 

Standard. 





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53 



SQUARE THREAD 



— f 




6 -* 



/? = PITCH OF THREAD =14- NO. OF THREADS PER »NCH. 

/^= DEPTH OF THREAD = ^, A 5 =^ 

Z7-OUTSIDE DIAM. 

y=EFFECTJVE DIAM. AT ROOT = Z!)-^/^ = Z?-/? 



OIAM OF 
SCREW 


1 


S 


3 
8 


/6 


1 


s 

8 


3" 
4 


7 
8 


» 


'5 


'^ 


'1 


'i 


THREADS 
PER INCH 


/O 


3 


a 


7 


6 


H 


s 


^k 


4- 


32 


3^ 


3 


3 






























DIAM OF 
SCREW 


'1 


'1 


'^ 


a 


-4 


4 


-% 


3 


^i 


-i 


-1 


A 




THREADS 

PER \NCH 


-i 


-5 


^i 


4 


Z 


Z 


•1 


'^ 


'1 


'1 


'i 


'i 





ACME STANDARD THREAD 




/>= PITCH OF THREAD = l-f NO. OF THREADIS PER INCH. 
ZJ=OUTSlDE DIAM. OF SCREW. <^= DIAM. OF SCREW AT ROOT, 



NUMBER OF 
THREADS 
PER INCH 


h 

DEPTH OF 
THREAD 


/ 

WIDTH AT 

POINT 


1 


,5\Q0 


.3 707 


1/3 


.3850 


.2780 


2 


.2fcOO 


. 1853 


3 


.1 7G7 


. / 235 


4 


.1350 


.0927 


5 


.1 100 


.0741 


6 


.0933 


.0GI8 


7 


.0814 


.0529 


8 


.07Z5 


.0463 


3 


,0Q>55 


.04I3 


lO 


.oeoo 


.037 1 



/?= DEPTH OF THREAD= 



^D- 



2XN0.THDS.PER IN. 
I 



4-.0I 



NO.OF THDSPERIN 
.3707 



.OZ 



/^=WIDTH AT P0INT=-^^^^ ^^,3 ^^^ ,^ 

rO DRAW THE ACME THREAD, FIRST 
LAYOFF THE SUCCESSIVE PITCHES, 
FROM THESE POINTS MARK OFF THE 
POINT WIDTHS /. THROUGH THE TWO 
SETS OF POINTS THUS FOUND 
DRAW LINES AT 30 AS SHOWN. 
THIS IS SUFFICIENTLY CLOSE FOR 
A DRAWING. 



Plate O. 



54 




Platx p. 



55 



PROPORTIONS FOR U.S. STANDARD 

SCREIW THREADS AND NUTS 

HOOPES AND TOWNSEND'S STANDARD SIZES FOR BOLT HEADS 


DIAM 

OF 

BOLT 

D 


BOLT THREADS 


NUTS 


HEADS 1 


THDS. 

PEP 

INCH 

N 


DIAM. 

AT 
ROOT 


AREA 

AT 
ROOT 

A 


THtCK 

HEX. 

OR SQ. 

T 


HEX. 

LONG 

DIAM. 

C 


SQ. 
L.ONS6 
DJAM. 

c 


HEX, SQ. 
SHORT 
DIAM. 


HEX. OR SQ. 


COUNTERSUNK 


SHORT 
DIAM. 

F 


THICK 
H 


D»AM. 


THICK- 
H 


1 
4- 


20 


.I8-5- 


.OZG 


A- 


37 
<&4 


45 
64 


1 
2 


3 
8 


3 
/6 


1 

2 


1 
8 


5 


I 8 


.240 


,OA5 


5 


1 / 
i 6 


27 
32 


19 
32 


15 
32 


/5 
64 


9 
/6 


3 


a> 


1 <^ 


.294 


.067 


3 
8 


5( 
64 


63 
G4 


i( 
16 


9 
/6 


3 
32 


/6 


3 

r6 


7 


I 4 


.344 


.092 


7 
/6 


7 
S 


1 ^ 
64 


25 

3Z 


2/ 
32 


21 
64- 


3 

4 


7 

76 


1 
2 


'^ 


400 


.125 


1 

Z 




1 '-^ 
'64 


7 
6 


3 
4 


3 
8 


7 
8 


1 
4 


9 
/6 


1 2 


.454 


.161 


9 
/6 


. 1 
' 8 


1 2^ 
'64 


3J 
32 


27 
32. 


27 
64 


L5 

16 


1 
4 




If 


.507 


.201 


5 
8 


1 — 


, 1 
' 2 


, 1 
' 16 


15 
16 


15 
3Z 


'i 


I 
4 


4- 


10 


.620 


.30/ 


3 


, 7 
' 16 


,49 
'64 


' 4 


, 1 

'a 


9 
16 


'i 


3 

8 


7 
8 


9 


.73, 


.419 


7 

a 


,21 
' 3Z 


^ii 


, 7 
' /6 


1 ^ 

'/6 


32 


'1 


7I 




a 


.83-' 


.B50 




, 7 


2 a 


' a 


, 1 
' 2 


3 

4 


'1 


1 

z 


, 1 
' 8 


7 


.940 


.6)93 


. 1 
'a 


^S^Z 


^?. 


' 16 


f " 
'/6 


27 
32 


@ 


, 1 
'A 


7 


1.0 CS 


.890 


. 1 
'4 


^/i 


^g 


2 


1 7 
8 


15 
16 


1 ^ 

'a 


G 


I.KoO 


\.05(S 


, 3 
'a 


-3^1 


^3^ 


^/i 


^;i 


'32 


, 1 


& 


l.ZB^ 


1.294 


'"z 


-5 


3||- 


2i 


^i 


, 1 
'8 


1 ^ 

8 


4 


1.3 89 


1.5/5 


.5 

' 8 


-li 


3| 


^1 


^^. 


, 7 
3 2 


\ 4- / 


1 ^ 


5 


1.49 1 


1.746 


1 ^ 

'4 


^^6 


3^ 
^64 


^1 


^f 


1 ^ 
'16 


\ 


t 


/ 




-^D > 




, 7 
' 8 


5 


\.(o\<o 


2.051 


, 7 
•a 


-it 


4^ 
^32 


^'A 


2f^ 


,13 
'32 


2 


^ 


1.7 12 


2.30J 


2 


3i 


4^ 

^4 


4 


3 


Z 


— <zzs^ 




^i 


^i 


I.9fc2 


3.023 


2i 


^4 


-*I4 


4 


IRON SET SCRENA/S 
AAA.-/ \ '''^ 


H 


4 


2.176 


Z.7/& 


4 


4-i 


^li 


^i 


W WW vvwvv\ 

^ L_ ><H -> 


\> 


^i 


4 


2.426 


4.622 


^1 


^n 


6 


4i 


3 


^i 


2.629 


5.428 


3 


^i 


S^I 


^1 


REGULAR SQ. 1- 


<EAD 


3i 


H 


2.879 


6.5 09 


^i 


-/I 


^ii 


5 


CUP OR ROUND POINT 
THREADS U.S. STANDARD 
F-=H, SAME AS DIAM.OF 

DIAMETERS FROM^ TO 1^ 
1 c Kit — ri-j iiMr^co i-jc"AP»— 1 


^i 


H 


3. /GO 


7.547 


4 


^6\ 


^a 


4 


5^ 


3 


3.3/8 


8.64/ 


^1 


^M 


«i 


-1 


4 


3 


3.567 


9.993 


4 


-3% 


«ti 


-; 


VAFKM 


:5 FRC 


Mj 


Yto, 


"1 



Plate Q. 



56 



STANDARD MACHINE SCREWS 


AMERICAN 5CREW COMPANY 


FLAT HEI/KO ROUND HEAD P^ILLISTER HEAD 




/Ni^ 


- 


H< 


7^ 


D* 


^K 


^C 




t I.I IN 






t 1,1 / 




2 


« 


r 


< llll 


1 ^^ 


" < lif 


< flf 


\ iG 


^ri 


\ 






V ' 


V 






-F 


-*If1- 


-* 


fk- 




NO 


A 


FLAT HEAD 


ROUND HEAD 


FILLISTER HEAD 


B 


C 


E 


F 


B 


C 


E 


F 


B 


C 


D 


E 


F 


2 


.0842 


.1631 


.0454 


.030 


.OI5i 


.I544.( 


7672 


.030 


.O403 


.1 350 


.054 s 


.01 26 


.030 


.0338 


3 


.0973 


.1894 


.0330 


.032 


0177 


.I786.C 


?74 6 


.032 


.OA48 


.1561 


.0634 


.0l4fe 


.032 


.039O 


-4 


.1 105 


.2158 


.O605 


.034 


.0202 


.2028.C 


)820 


.034 


.0492 


.1772 


.o7ac 


.0166 


.034 


.0443 


5 


.I23G 


.2421 


.068I 


.036 


0227 


.2270 .C 


)894 


.036 


.0536 


.1984 


.080€ 


..0186 


.036 


.0496 


& 


.1368 


.2684 


.0757 


.039 


0252 


.2512 .C 


>968 


.033 


.0580 


.2195 


.0892 


.0205 


.033 


.0549 


7 


.I500 


.2947 


.0832 


.04I 


0277 


.2 754 .1 


042 


.04 1 


.oe>2S 


.2406|.0978 


.0225 


.04I 


.0602 


8 


.1631 


.3210 


.O90Q 


.043 


0303 


.2996.1 


1 16 


.043 


.0670 


.2617 


|.»Ofe3 


.0245 


.043 


.0654 


9 


.1763 


.3474 


.0984 


.045 


0328 


.3238 .1 


190 


.045 


.0 714 


.Z&ZB 


.1149 


,0265 


.045 


.0707 


lO 


.1894 


.373 7 


.1059 


.048 


0353 


.3480.1 


264 


.048 


.0 758 


.3040 


.1235 


.0285 


.04-8 


.0760 


12. 


.2158 


.4263 


.I2IO 


.052 


0403 


.392.Z .1 


412 


.052 


.0847 


.3462 


.IA07 


.0324 


.052 


.0866 


14 


.2^21 


.4790 


.1362 


.057 


0454 


.4364, 


5.0 


.057 


.0936 


.3884 


.1578 


.0364 


.057 


.097/ 


IG 


.2684 


.5316 


.1513 


.061 


0504 


.4806 . 


708 


.06I 


.1024 


.4307 


. 1 75C 


.0403 


.Ofel 


.1077 


18 


.2947 


.5842 


.1665 


.066 


0555 


.5248 .1 


8 56 


.Qbb 


.1 1 14 


.4 72 9 


.1921 


.0443 


,066 


.1182 


20 


.3210 


.6368 


.1816 


.070 


0G05 


.5690.J 


004 


.070 


.1202 


.5152 


.209.3 


.0483 


,070 


.1288 


22 


.34 74 


.6895 


.1967 


.075 


0656 


.6I06 .1 


152 


.075 


.1291 


.5574 


.2 267 


.0520 


.075 


.1384 


24 


.3737 


.7421 


.21 18 


.079 


0706 


.6522 .i 


>3O0 


.079 


.I380 


.5996 


.2436 


.0562 


.079 


.1499 


26 


.4 GOO 


.7421 


.1967 


.084 


0656 


.6938 .2 


448 


.084 


.1469 


.6419 


.26>oe 


.060I 


.084 


.I6O5 


28 


.4263 


.7948 


.2118 


.088 


0706 


.7354 .2 


596 


.088 


.1558 


.6841 


.Z773 


.0641 


.088 


.1710 


30 


.4526 


.8474 


.2270 


.093 


0757 


,7770 .c 


744 


.093 


.1646 


.7264 


.2951 


.0681 


.093 


.1816 


MACHINE SCREWS ARE DESIGNATED THUS-'^IZxaO F1\_\_I5TER 


HEAD MACHINE SCREV^S'' WHICH MEANS SIZE (GAUGE) *^I2 HAVING 


20 THREADS PER INCH THEREON. SEE LAST COLUMN IN THE 


TABLE OF STANDARDS FOR WIRE GAUGES. 


THE NUMBER OF THREADS PER INCH FOR THE VARIOUS SIZES 


WILL BE FOUND IN THE FOLLOWING TABLE. 


NO 


THREADS PER INCH 


NO 


THREADS PER INCH 


a 


64 


56 


48 


. . 


, , 


. . 


, , 




1 z 


24- 


20 


, . 


. , 










3 




56 


48 


. . 


. . 


. . 


. . 




14 


24 


20 


1 8 


. . 










4 








40 


3<o 


32 


. . 




1 6 




20 


Id 


1 6 










5 








4-0 


36 


3Z 


. . 




. 18 




20 


16 


16 










6 










36 


32 


30. 




. 20 






18 


1 6 










7 










. . 


32 


30 




. zz 






IS 


16 










8 










36 


32 


30 




. 24 






1 8 


1 6 


»4 








9 










. . 


32 


30 


£" 


^ 26 






, . 


1 6 


14 








lO 












32 


30 


2' 


\ 26 
30 








1 6 
16 


14- 

4 









Plate R. 



57 



TAPERS. 1. When it is desired that two or more pieces shall 
fit tightly and at the same time be readily adjustable for taking up 
wear or for removing, one or more of the pieces are made tapering. 

2. The necessary dimensions are those of the larger end, the 
length of the tapered portion and the taper per foot, or fraction of 
an inch in a whole number of inches, i. e., J'' in 5". (See Fig. 33.) 

3. On a tapered piece, that does not fit anything, give the 
size at each end and its length. The rate of taper must not be given. 



Taper ^/n per Ft 




Taper —Jn.per Ft 




Always ^/i/e the 
Taper per Ft _ 
in aafc/it/on to 
the c/imensior?s 
shoi/yr? 





a 



Fig. 2,3. 

4. There is no universal standard for tapers, different lines of 
work and different shops adopt tapers suitable to their require- 
ments. The following, used in locomotive practice, is a fair sample: 
Bolt Taper -h" in 12". Boiler Taps 1" in 12". 
Cross-head Pins Y in 5". Brass Cock Plug 2Y in 12". 
Cross-head Key f " in 8' 
Connecting Rod, Stub Keys and Cotters 

STANDARD STEEL TAPER PINS. 1. These pins, made by 
Pratt and Whitney Co., taper \" per foot, and lengths vary by \". 



Cross-head End of Piston Rod Y in 5". 



f"in 12". 



Size No. 

Large Diam. 0.156 
Length 4-I 



0.172 



2 
0.193 



3 
0.219 



4 
0.250 



5 6 7 8 9 10 

0.289 0.341 0.409 0.492 0.591 0.706 
^2i ^-3i l-3i \\-A\ \\-5\ \\-^ 



5S 



I-P.PE 




CONVENTIONAL METHOD TO BE 
5ED WHEN D, AFTER BEING 

DRAWN TO SCALE, MEASURED 

LE55 THAN ONE INCH. 
PIPE THREAD TAPERS I IN 31 TO AXI3. 
OrJ"|N DiAM. 
PER FOOT. 
DRAW PIPE 
THREADS 
AS SHOWN. 
ACTUALLY 
THE THP5, 
FURTHEST 
FROM END 
ARE NOT 
PERFECT, 
SEE TABLE 




\//ROUGHT IRON STEAM, GA5 AND WATER PIPE 

NATIONAL tube: COMP/VNY — STANDARD DIMENS\ONS 



DIAMEITEIRS 



NOMINAL 
INTERNAL 



ACTUAL- 



INTERNAL- 



STAN 
DARD 



EXTRA 
HEAVY 



EXTER 
NAL 



TRANSVERSE 

INTERNAL 

AREAS 



5TAN 
DARD 



EXTRA 
HEAVY 



THREADS 



NO 
PER 
INCH 



LENGTH 
THREADED 



LENGTH 
PERFECT 
AT ROOT 



DRILL 
HOLE 
FOR 
TAP 



% 

I 

2 

3 

3'/, 



7 
8 

3 
10 
I I 
/2 



270 
.364 
.494- 
.62 3 
.824 
1.048 
/.3SO 
t.&l I 
Z.O(ol 
2.4 6 8 
3.0 6 7 
3.54 8 
4.0 2 (o 
45 O 8 
5.045 

1.02 3 
7.982 

8.3 3 7 
/ 0.0 I -9 
I I.OOO 
I 2.0O0 



Z05 

.42 I 
.54 2 
.736 
.35 I 
1.272 
1.434 
i.933 
2.3 IS 
2.892 
3.358 
3.8 1 8 
4.2 80 
4.81 3 
5.7 5/ 
6.625 
7625 
8.62 5 
9.750 

I 1.750 



A05 

.54 

.675 

.84 

1.050 

1.3 1 5 

1.660 

1.900 

2.375 

2.8 75 

3.50O 

4.000 

4.5 
5.000 
5.5-6 3 

6.6 2 5 
7.6 25 
8.6 25 
3.6 2 5 

lOJSO 
i 1.750 
/2.750 



.05 7 

./04 

.19 I 

304 

.533 

86 1 

1.496 

2.036 

3.356 

4.780 

7.383 

9.8 87 

1 2.730 
15.961 
19.985 

2 8.88 6 

3 8.743 
5 0,0 2l 
62.722 
78.822 
9 5.034 

//3.090 



.0 3 3 

.068 

.^ 33 

.231 

.425 

.7/ O 

1.271 

1.753 

2.935 

4.2 03 

6.569 

8.856 

1 /.449 
14.387 
18.193 

2 5.976 

3 4.47 2 
45.664 
58.4 2 6 
74.662 



108.430 



27 

18 
18 
14 
14 

ll'/2 
11'/, 

..'4 

8 
& 
8 
8 
8 
8 
8 
8 
8 
8 
8 
8 
8 



%^ 



//6 
5/ 






''/8 
''4 

''4 
^\ 



'4 

'>64 

•'4 
r% 
'\ 
'%, 
/\ 
1% 
1% 



% 
% 

/% 
^% 

Z% 
3^ 

4^* 

4% 

<&^ 

7^6 
S\ 
^\ 

I l7/fc 
12^/6 



Pl.\te S. 



59 



PIPE. 1. Iron pipe is always specified by its nominal inter- 
nal diameter. By referring to the pipe table it will be seen that the 
actual sizes differ from the nominal. Use actual sizes on drawings. 

2. A pipe tapped hole is shown in plan by two circles, the 
inner one being full and equal to the drill size, the outer one half 
full and half dotted and equal to the outside diameter of the pipe. 
(See illustration on Plate S.) 

3. Tubes of iron, steel, brass or copper are specified by their 
outside diameter and the gauge number corresponding to the 
thickness of the material; thus 2" brass tube 12 B. & S. gauge. 



STANDARD GAUGES. 1 

and Screws are given in Plate T. 



Standard gauges for Wire, Plate 



WEIGHTS OF CASTINGS AND FORGINGS. It is often 
required to find the approximate weight of a piece of machinery, 
especially for making estimates from drawings. This is done by 
finding the volume and multiplying by the specific weight of the 
material of which it is to be made. As results within 10 % of 
actual weight are considered satisfactory in practice, it is not 

WEIGHTS OF METAl_S 



BRASS 

broisjzie: and corpezr 

CAST IRON 

CAST STEEIL. 

LEZAD 

WROUGHT IRON AND STEEL. 



VVEIGMS 



.03^^ PER CU. IN, 
.30^ It 1 

.3 1^ 
.2 6 « // 



.za' 




Fig. 34. 



necessary to consider small fillets and other minute details. Divide 
the piece into a number of parts, the volumes of which are readily 
obtainable. If close estimating is required or if there are numerous 
fillets of some size, they should be taken into account. (See Fig. 34.) 



60 



STANDARDS FOR.WIRE GAUGES 









IN USE IN THE UNITED 


STATES 


DIMENSIONS ARE IN DECIMAL PARTS OF AN INCH 


1 U 
^ ^ 

9 ^ 












UJ 


u 

li 


AMERICAN 

OR BROWN 

AND SHARPE 


BIRMINGHAM 
OR STUBS 
ENGH5H 


u 
q: 

Si 

(0 ^ 

\- 


Q 
< h 

P 

^ p 


ol 

C or UJ 

Ili vD 
£3 > D 

z u 


5 < 

< 

T ^ 


000000 
00000 

oooo 


.46 






.4688 
.4375 
.4063 


ooocoo 

00000 

oooo 






.454- 


ooo 


.^096 


.4Z5 





. 3 750 


000 


.03I 5 


00 


.3648 


.38 




.3438 


00 


.0447 





. 3249 


.34 




.31 2.5 





.0578 


1 


.2893 


.3 


.227 


.281 3 


I 


.07/0 


2 


.2576 


.2 84 


.z\e 


.2656 


2 


.0842 


3 


.2 Z9A 


.259 


.2 1 2 


.25 


3 


.0973 


4 


.2043 


.238 


.201 


.2344 


4 


./ 1 05 


5 


.18 19 


.22 


.2 04 


.2188 


^ 


. 1236 


G 


. 1 620 


.203 


.20I 


.203/ 


fa 


.1368 


7 


. / 443 


.18 


.1 99 


.1875 


7 


. I500 


8 


.1 28S 


.1 65 


.1 91 


.I7i9 


8 


. 1 631 


3 


.1 14-4 


.148 


.1 94 


./ 563 


9 


. 1 763 


10 


.IOI9 


.1 34 


191 


.1406 


10 


. 1 894- 


M 


.0907 


.1 2 


.188 


. 1 Z5 


1 1 


.2026 


12 


.0808 


./09 


.185 


A 094 


12 


.2 158 


13 


.0720 


.095 


.1 82 


.0938 


1 3 


.2289 


1-4 


.064I 


.083 


.1 80 


.078I 


14 


.2421 


13 


.057I 


.072 


.1 78 


.0703 


15 


.25-52 


16 


.0508 


.065 


.175 


.06E5 


1 6 


.2 6 8-* 


17 


.045S 


.058 


.172 


.0563 


17 


.2816 


18 


.04-03 


.049 


.168 


.05 


18 


.2947 


19 


.0339 


.042 


.1 64 


.0438 


19 


.3079 


ZO 


.0320 


.035 


.1 61 


.0375 


ZO 


.32 1 


21 


.0285 


.032 


.1 57 


.0 34-4 


2 i 


.3342 


22 


.0253 


.028 


.1 55 


.03I 3 


22 


.3 4 74 


23 


.0226 


.025 


.153 


.028I 


23 


.3605 


24 


.020 1 


.022 


A 51 


.OZ5 


24 


.3737 


Z5 


.0\ 79 


.02 


.148 


.OZl 9 


ZS 


.3868 


26 


.OJ59 


.01 8 


.1 46 


.Ol 88 


26 


.4000, 


27 


.0»42 


.0\ 6 


.143 


.0/ 72 


27 


.41 32 


28 


.0\ 26 


.014 


.1 39 


.Ol 5i» 


Z& 


.4263 


29 


.Ol 1 3 


.Ol 3 


.1 34 


.0140 


29 


.4395 


30 


.0 1 OO 


.0 12 


.1 27 


.OI25 


30 


.-4526 


31 


.0O89 


.O 1 


.1 20 


.0/ 09 


31 


.4658 


32 


,ooao 


.009 


.1 15 


.o; 02 


32 


.4790 


33 


.001 1 


.008 


.1 1 2 


.0094 


33 


.4921 


34 


.0063 


.007 


.1 1 


.0086 


34 


.505 3 


35 


.OOS6 


.003 


./ 08 


.0O78 


35 


.51 84 


36 


.005 


.004 


.1 06 


.0070 


36 


.531 6 


37 


.0045 




.103 


.0066 


37 


.5448 


3 8 


.0040 




.1 Ol 


.0O63 


38 


.5579 


39 

40 


.0035 
.003I 




.099 
.097 




39 
40 


.57 1 1 
.5842' 







Plate T. 



61 



DECIMALS OF AN INCH FOR EACH 64 


TM 


32no& 


64ths. 


DECIMAL 


FRACTION 


32nds. 


64ths. 


DECIMAL 


FRACTION 




1 


,Oj5625 






33 


5(5625 




1 


2 


.03I25 




17 


34 


.53125 






3 


.046875 






ZS 


.546875 




2. 


4 


.0625 


1-16 


(8 


36 


.5625 


S-16 




5 


.078J25 






37 


.578/25 




3 


6 


.09375 




19 


38 


.59375 






7 


-lOSaZS" 






39 


.609375 




A 


8 


.125 


1-8 


20 


40 


.625 


5-8 




9 


.(40625 






41 


.640625 




5- 


10 
1 1 


.15625 
.171875- 




21 


42 
43 


.65625 
.671875 




6 


la 


.1875 


3-16 


22 


44 


.6875 


11-16 




13 


.203/2S 






45 


y02>\ZS 




7 


14 


.2 1875 




23 


46 


.7I&75 






IS 


.234375 






47 


.734375 




8 


16 


.25 


1-4 


24 


48 


.75 


3-4 




17 


.265625 






49 


.765625 




9 


f8 


.28125 




25 


50 


.78125 






iS 


.296875 






51 


.796675 




JO 


EO 


.3125 


5-16 


26 


52 


.8125 


I3~I6 




Zl 


.328125 






53 


,828/25 




1 1 


22 


.34375 




27 


54- 


.84375 






23 


.359375 






55 


.859375 


, 


12 


24 


.375 


3-8 


28 


56 


.875 


7-8 




25 


.390625 






57 


.89062S 




13 


26 


.4062 5 




29 


SB 


.90625 






27 


.42/875 






59 


.92/875 




14 


28 


.4375 


7-16 


30 


60 


.9375 


15-16 




29 


.453125 






6 1 


.953125 




15 


30 


.46875 




31 


62 


.96875 






3 1 


.484375 






63 


.984375 




16 


32 


.5 


1-2 


32 


64 


1. 


' 



Plate U. 



INDEX. 



PAGE 

Abbreviations — Fig. 18 19 

Arrangements of Views — Fig. 8, Fig. 9 . 9 

Arrow Heads — Fig. 16, Fig. 17 17 

Assembly Drawings 39 

Bill of Materials— Plate G 34 

Blue-prints 41 

Bolts— Plates P, Q 51 

Choosing the Proper Scale — Fig. 10... 11 

Conventional Threads— Fig. 32 50 

Courses 4 

Cross-hatching — Fig. 20, Plate A 20 

Decimal Equivalents — Plate U 61 

Department Standard Sizes, Fig 7, . . . . 8 

Dimensioning — Fig. 16, Fig. 17 17 

Erecting Drawings 40 

Extension Lines 18 

Figures — Fig. 16 17 

Finish Marks — Fig. 19 19 

Fractions — Fig. 16 17 

Gears — Plates L, M 45 

Inking In 15 

Instruments — Fig. 1, Fig. 2, Fig. 3, . . . 5 

Intersections — Fig. 22, Fig. 23 29 

Lettering— Fig. 24, Fig. 25, Plate E... 33 

Line Shading— Fig. 21, Plates B, C, D 23 

Lines— Fig. 11, Fig. 12, Fig. 13 12 



P.\GE 

Machine Screws — Plate R 51 

Number Circle — Fig. 4 7 

Pipe—Plate S 59 

Preface 3 

Screw Threads— Fig. 28, Fig. 29, 

Fig. 30 48 

Screw Threads. Proportions and 

Tables— Plates N, O 51 

Sections — Fig. 15 19 

Shade Lines— Fig. 14 14 

Size of Sheets— Fig. 5, Fig. 6 7 

Sketches— Fig. 26, Fig. 27 41 

Sub-Captions— Plate G 34 

Tabulated Dimensions — Plate J 18 

Tapers— Fig. 33 57 

Taper Pins, Standard 57 

Tapped Holes— Fig. 31 50 

The Essentials 9 

Tinting 22 

Titles— Plate F, G, H, K 34 

Tracings 40 

Trimming Drawings 9 

Weights of Castings and Forgings — 

Fig. 34 59 

Wire and Screw Gauges — Plate T 59 



(63) 



n 



LIST OF ILLUSTRATIONS 



FIGURE 


PACK 


1 — Instruments in Cast- 


... 5 


2 — Irregular Curve 


6 



3 — Use of Triangles 6 

4 — Number Circle 7 

5 — Size of Sheets, Course 492, first 

term 7 

6 — Size of Sheets, 

Course 492, second term 8 

493, first term 8 

7 — Size of Department Standard 

Drawings 9 

8 — Object Surrounded by Planes 10 

9 — Position of Views 10 

10 — Locating View< 1 1 

11— Lines 12 

12— Dotted Lines. (Ending) 12 

1 3— Piston 13 

14 — Shade Lines 14 

1 5 — Coupling 16 

1 6 — Size of Figures and Arrows 17 

1 7 — Dimensioning Small Spaces IS 

1 8 — ^Abbreviations and Symbols 19 

19— Finish Marks 19 

20 — Breaks in Long Pieces 22 

21 — Line Shading. (Theory) 24 

22 — Intersection of Cylinders 29 

23 — Intersection of Elbow and Cyl- 
inder 31 

24 — Block Letters 33 

25 — Sixty degree Letters. (Course 

492) 33 

26— Sketch 39 

27— Sketch. (Details) 40 



FIGURE PACE 

I 28— Screw Thread. (Helix) 48 

29— Screw Threads. (R & L, V 

I &Sq.) 49 

I 30— Section Through Threads 49 

31— Tapped Hole 50 

32 — Conventional Threads 50 

33— Tapers 57 

34 — Weights of Metals 59 

PLATE 

A — Conventional Standard Cross- 
hatchings 21 

B — Line Shading. (Examples) 26 

j C— Line Shading. '* 27 

I D— Line Shading. 28 

j E— Lettering 32 

i F— Titles. (General) 35 

G — Titles, Sub-Captions, Bill of 

Materials 36 

H— Titles. (Course 517) 37 

J — Tabulated Dimensions 38 

K— Titles. (Course 494, second term) 39 

L — Drawing the Involute Tooth 46 

M — Drav^'ing Bevel Gears 47 

X— U. S. & V. Standard Threads. 

(Proportions) 52 

O — Square and Acme Standard 

Threads (Proportions) 53 

P— Bolt Heads and Nuts 54 

Q— U. S. Screw Threads and Nuts ... 55 

R — Machine Screws 56 

S— Pipe Table 58 

T — Wire and Screw Gauges 60 

U — Decimal Equivalents 61 



(64) 



v> >9\* 






f;'?RARY OF CONGRESS 
II III mil IlillllllMM.t 



019 970 358 4 



^ 



